public class test
{
    public static void main(String[] args)
    {
        People p = new People();
        p.speak();
        p.ID();

        p=new Teacher();
        p.speak();
        p.ID();

        p=new Student();
        p.speak();
        p.ID();
    }
}

class People
{
    void speak()
    {
      System.out.println("我是人");
    }

    void ID()
    {
      System.out.println("我是普通人");
    }
}

class Teacher extends People
{  
    void ID()
    {
      System.out.println("我是老师");
    }
}

class Student extends People
{  
    void ID()
    {
      System.out.println("我是学生");
    }
}
